Grinding machine



Jan. 21, 1964 P, D] LELLA 3,118,254

GRINDING MACHINE INVENTOR'- PAUL D LELLA,

BY ,0. Vm/wmyumw HIS ATTORNEY.

Jan. 21, 1964 P. Dl LELLA GRINDING MACHINE l2 Sheets-She Filed March 22, 1961 INVENTORI PAUL. DLELLA,

BY O-'mmmpw Hls ATTORNEY.

Jan. 21, 1964 P. DI LELLA GRINDING MACHINE 12 Sheets-Sheet 5 Filed March 22, 1961 RH.. O E .M L E .nm V L NU l A P Hls ATTORNE Jan. 21, 1964 P. Dl LELLA GRINDING MACHINE l2 Sheets-Sheet 4 Filed March 22, 1961 N Ox INVENTOR: PAUL DiLELLA,

BY ,(9. P11-fw HIS ATTORNEY.

Jan. 21, 1964 P. DI LELLA GRINDING MACHINE 1,?, Sheets-Sheet 5 Filed March 22, 1961 INVENTOR' PAUL DiLELLA,

` BY y HIS ATTORNEY.

Jan. 21, 1964 p, D1 LELLA 3,118,254

GRINDING MACHINE Filed March 22, 1961 l2 Sheets-Sheet 6 I7 INVENTORZ PAUL. DLELLA,

BY HIS ATTORNEY.

Jan. 21, 1964 P. D1 LELLA GRINDING MACHINE 1,2 Sheets-Sheet 7 INVENTOR'.

n PAUL DLELLA,

Filed March 22, 1961 HIS ATTORNEY.

Jan. 21, 1964 P. Dl LELLA GRINDING MACHINE l2 Sheets-Sheet 8 Filed March 22, 1961 HIS ATTORNEY.

Jan. 21, 1964 P. DI LELLA GRINDING MACHINE l2 Sheets-Sheet 9 Filed March 22, 1961 INVENTOR: PAUL DiLELLA, BY A9. www

HIS ATTORNEY.

Jan. 21, 1964 P. Dl LELLA v3,118,254

GRINDING MACHINE Filed March 22, 1961 1,2 Sheets-Sheet l0 -267 FIG. IA.

268 27o 272 260 J2e.: -`Q il QT-H j 26a 50s I 459 I O i l NQ QI Q 507 457 46l\: 458 ci, 460 g f) (L O )C 294 237 ITO-[ J` u2 396 392 lNvENToR: 3,8 329 PAUL DILELLA,

VWM

Hls ATTORNEY.

Jan. 21, 1964 P. Dl LELLA GRINDING MACHINE l2 Sheets-Sheet 11 Filed March 22, 1961 INVENTORI PAUL DILELLA,

HIS ATTORNEY.

Jan. 21, 1964 P. D1 LELLA 3,113,254

GRINDING MACHINE Filed March 22, 1961 l2 Sheets-Sheet 12 ff INVENTOR:

PAUL DiLELLA,

HIS ATTORNEY.

tetes This invention relates to an improved grinding machine for i ing the sides of multi-sided Work pieces automatically, and removing a uniform thickness of material from the work piece. The invention is illustrated herein as a grinding machine intended particularly for grinding steel billets.

In the manufacture of alloy and tool steel, the molten steel is poured into a mould to cast an ingot, containnsually a number of tons of steel. This ingot is heated and passed through a roll mill to effect elongation of the b; et and to reduce its cross sectional dimension in the order of from two to six inches. This elongated piece is cut into lengths approximately six feet long, and the pieces are referred to as billets. These billets are again re-heated and then rolled or drawn down to a desired cross sectional dimension for the formation of cutters, tools, etc. Because of rolling the large ingot under extremely high pressure, the billets are covered with a sln of scale, and also the high pressure rolling develops ilaws in the billet in the form of checks and cracks.

Before the billets can be re-rolled, it is necessary to remove this scale and any such flaws that may exist. Heretofore, the billets have been ground to remove the scale and flaws by manual manipulation of a free suspended grinder. This embodied a great deal oi manual labor and a considerable waste of steel, in that the removal of the scale was according to the judgment of the operator or" the manually manipulated grinder.

Vere recently, machines have been developed for automa "ally grinding billets and with the aim of removing a uniform thiclmess or" material. These machines have not functioned satisfactory due to the fact that the structural arrangement involved and the control mechanism did not function to maintain, within close limits, a uniform pressure between the grinding wheel and the billet. Without proper control this pressure necessarily varie due to the fact that the billets are invariably not straight, but more oit-en warped, bent, or otherwise of crooked form whereby, to remove a uniform thickness of material, the arrangement has to be such that a uniform preset pressure will be maintained while the grinding wheel is to lov/ing the contour oi the billet. The prior machines, lacking this close control, accordingly did not properly grind the billets and also caused a waste of steel.

This imv on has as an object a grinding machine embodying a structural arrangement and control mechanism by which the machine can be set to remove any desired uniform thickness or" material from the sides of the billet, this being accomplished by adjusting the machine to establish a preset pressure between the grinding wheel and the surface of the billet being ground, and that pressure will be maintained automatically, within exceedingly close limits, regardless of the contour of the billet.

The invention has as a further obiect a grinding machine of the type referred to capable of being quickly and conveniently adjusted by a single means to establish a predetermined pressure between the wheel and the Work piece.

The invention has a further obiect an improved mechanism for clamping the billets to the reciprocating table, and for automatically turning the billets to present the sides of the billets successively to the grinding wheel.

llggfi Patented Jan. 2l, i964 The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the ccompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings:

FIGURE 1 is a front elevational view of a grinding machine embodying my invention.

FtGURE 2 is an end elevational view of the machine looking to the right, FIGURE 1.

FEGURE 3 is a top plan view.

FIGURE 4 is a view taken on line 4 4, FIGURE 1.

FIGURE 5 is an isometric view of the grinding Wheel mount structure.

FlGURE 6 is an enlarged end elevational View of the rear portion of the machine, taken on line 6 6, FIG- URE 3.

FIGURE 7 is an enlarged top plan view of one of the billet clamping and turning structures.

FIGURE 8 is a view talten on line 8 8, FIGURE 7,

FGURE 9 is an enlarged top plan View of the structure appearing at the left portion of FIGURE 7.

FIGURE l0 is a side elevational View looking up in FIGURE 7.

FIGURE 1l is a view taken on line 11-11, FIG- URE, 9.

FIGURE 12 is Ka view taken on line 12 l2, FIG- URE 9.

FIGURES 13A and 13B constitute a schematic wir-ing diagram of the electrical control circuit. -In reading these gures, FGURE 13B is placed to the right of FIG- URE 13A.

FGURE 14 is a view indicated by line id lfl, FIG- URE 6.

lFlGURlE 15 is a view taken on line 1S 1S, FIG- URE I4.

EEGURE 16 is a view taken on line 16 l.6, FIG- URE 6.

vlFIGUlJE. 17 is a View taken on line 17 17, FIG- URE 6.

FIGURE 18 is a View taken on line 18-18, FIG- URE 6.

In general, `the invention comprises a table having means for `clamping the work piece, or billet, in fixed position, and means for effecting reciprocation of the table in a direction lengthwise of the billet. A carriage is mounted for movement toward and from the table in a direction transversely thereof. A support mem-ber is mounted on the carriage for vertical movement, and a grinding wheel mount is carried by said support and ls arranged to have lirmted vertical movement relative to the support, and means is provided for yieldingly urging the mount downwardly relative to the support. The carriage is moved forwardly, or toward the table, to position the grinding wheel carried by the mount above the billet. The support is moved `downwardly to move the grinding fwheel into engagement with the front corner edge of the billet, at which time the table is being reciprocated to effect movement of the billet lengthwise While the grinding Wheel is in engagement therewith. Upon each reciprocation `of the table, the carriage is moved rearwardly, whereby the upper surface of the billet is ground. When the then upper surface of the billet tis completely ground, the wheel mount Support is automatically raised and the carriage moves forwardly and during this operation, the billet is unclamped and rotated to bring an adjacent side of the billet up, and the billet is automatically again clamped in this turned position. rihe cycle is then repeated until all four sides of the billet have been ground, whereupon the billet is released and discharged tfrom the clamping mechanism,

and a lnew billet is inserted therein. During the entire grinding operation, a predetermined pressure is automatically maintained between the grinding wheel and the billet. The control mechanism for the machine permits the operator at any time to take the machine out of automatic operation for manual control.

Referring to the drawings, the billet supporting table is mounted for reciprocation on a pair of bars 2t) circular in cross section `and extending in parallel spaced relation. These bars are supported at their ends by angie plate brackets Z1 having reinforcing ribs 2,2. The brackets 2l are iixedly secured to the ends of front and rear base beams 24, 25. The e-nds of the bars 20 are of reduced diameter extending through the angle plates 21 and being ixedly secured by nuts 26. The table structure consists of a pair of channel members 27 ixedly secured, as by welding, to a flat top plate 28. There are three shafts 36 xedly mounted in the middle portion of the members 27 and extend transversely thereof. On each end of the shafts 30, there are journalled rollers 3l, formed concave at their peripheries, for rollin-g engagement on the supporting bars 20, see FIGURE 4. Vertically disposed bars 32 yare xedly lsecured to cross plates 33 fixed to the base beams 24, 25, by angle plates 34. Bars 3S are xed to the upper ends of the bars 32 and extend lengthwise of the table and inwardly over the rollers 31. Bars 37 are `fixed to the bars 35 and have their lower edges formed convex for moving in close relation to the rollers 3'1. This arrangement prevents any upward movement of the table from the supporting rods 20. There are a number of plates 38 ywelded or otherwise fixed between the side members 27 of the table, and rI-beam 4t) is fixed to the plates 38 and extends lengthwise of the table. A gear rack 4l is fixed to the under side of the depending beam 4t), as by bolts `42. The front base beam 24 is o formed at its center with an opening in which there is mounted a gear reducing unit 43 having a laterally extending bracket 44 on which there is fixed a driving motor 45. The output shaft 46 of the gear reduction has afxed thereto la pinion 47 engaging with the rack 41. The motor 45 is a reversible motor and this arrangement is employed to effect reciprocation of the table in a lengthwise direction.

' The billets B are secured to the table by a pair of billet clamping structures, best shown in detail in FIGURES 7 to 12. There is aixed to the table top 2S a pair of guide members t? foreach clamping and turning mechanism, as by cap screws 5d. Side plates 52 are mounted in vertical edgewise position on the table top 28 and are formed on their inner confronting surfaces with lengthwise extending grooves to slidably receive outwardly extending ange portions 54 formed on the guide members Si?. Both billet clamping structures embody the same construction and therefore the explanation of one clamping structure will suice.

The billet yclamping and turning structures are mounted on the side plates 52, these structures including end plates 55, v56, extending in parallel spaced relation transversely of the table. A rear plate 57 is ixedly secured between the side plates 5S, 56, and a horizontally disposed plate 58 is xedly secured between the plates 55, 56, at the Afront ends thereof. A rectangular plate 6h is aixed to the inner surface of the side plate 55' and the back plate 57, the plate 66 extending horizontally coplanar lwith the plate 5d. These plates 53, 6i), are positioned on the upper edges of the members 52 and are axed thereto, as by screws 61.

The upper edges of the plates 55, 56, at the front portions thereof, incline downwardly as at 63, yand the rear portions of the top edges of the plates incline downwardly, as at 64. The intermediate portions of the side plates 55, S6, are formed with notches having downwardly and rearwardly inclined front walls 67 and upwardly and rearwardly inclined walls 63 merging with relatively short horizontal portions 69. A bar 7%, rectangular in cross section, is positioned in notches formed in the top edges of the plates 55, 56, intermediate the inclined surfaces 63, 67. This bar 7d is hxedly secured to the side plates, as by welding, the upper side of the bar being in line with the horizontal rear surfaces 69. rhe upper edges of the plates 55, 56, including the surfaces 63, 64, 67, 68, 69, are formed with lengthwise extending slots in which are ixedly secured hardened wear strips 72.

The side plates 55 are formed with depending portions 74, and the plate 58 is formed with a similar depending portion '75. These parts 74, 75, are formed with aligned apertures to receive a pin 76 forming a pivotal mount for a cylinder 77. An angle lever is pivotally mounted on a stud 78 fixed tto the side plate 55. This angle lever has an elongated leg portion 80, the upper surface of which normally extends in the plane of the bar 70, and the wear strip 72 on the edge surface 69. This angle lever has a depending leg portion S1 pivotally connected to a clevis l32 carried by the piston rod 83 of the cylinder 77, the forward end of which is mounted on the pin 76. When `iiuid pressure is applied to the free end of the cylinder, the angle iever Sti, 81, is Vin the position sho-Wn in FIGURE Svwith its upper edge in line with the bar .7@ and wear strip 72 Aon surface 6? of the side plate 55 for the support of a billet B. The forward end of fthe leg 8G is notched complemental to the b ai" 70, whereby the bar forms a stop for the leg 80 of the angle lever when it is in its raised position. An arm 34 is pivotally mounted on the stud 78. The forward end of the arm 84 is formed with a serrated jaw 85 for engaging the front vertical side of the billet B. Ihe under side of the arm `i341- is formed with an arcuate surface S7 engaged by a roller 88 journalled on a stud 89 atlixed to a link` 9i? pivotally mounted at is lower end on a stud 91 carried by the side plate 56. A jaw member 93 is pivotally attached Eto the upper end of the link 99.

A link 95 is pivotally connected at one end to the stud 89, the opposite end of the link being pivotaily connected to the upper end of a link 97 pivotally mounted intermediate its ends on a stud 98 carried by a boss 99 af- Xed to the inner surface of the side plate 56. The lower end of the link `97' is pivotally connected to a Clev'is 1d@ connected to a piston rod 10i of a cylinder 102. The forward end of cylinder 102 is pivotally mounted on a pin 193 carried by a bracket 194 depending fro-m plate 5d. In FIGURES y8 and 10, fluid pressure has been applied to the pivotal end of the' cylinder 162, moving the piston rod 161 to rear position and with the link 99 moved to the position shown with the jaw 93 engaging the rear side of the billet B and clamping it against the j'aw 85.

When fluid pressure is admitted to the free end of the cylinder, the piston rod 101 is moved forwardly, moving the upper end of the link 95 rearwardly, and moving the link 90 in a counter-clockwise direction about the pivot 3? to the position shown in FIGURE 1l. This eects rearward movement of the roller 88 and, because of the arcuate surface `$7 on the bottom side of the arm S4, the' arm is permitted to drop, moving its jaw l downwardly between the plates 55, 56, to the position shown itt FIGURE ll.

When the jaws 85, 93, have been opened to the position shown in FIGURE `ll to release the billet B, fluid pressure is admitted to the pivotal end of the cylinder 77, moving its piston rod S3 rearwardly, causing the arm Si) to drop downwardly so that the upper edge of the arm 8o assumes a position substantially co-planar with the inclined wear strip 72 on surface 68 of the side plates. Due to the fact that the forward bottom edge corner of the billet B, FIGURES 10 and l2, is positioned on thel xed bar 7h, the billet will now rotaite in a counter-clockwise direction and fall into the notches formed in the: side plates 55, 56, the rear side 107 of the billet, previously engaged by the jaw 93, now resting upon the; lncllned wear strip 72. In other Words, the billet has: made a quarter turn. When fluid is admitted to the free: end of the cylinder 77, moving the piston rod- 83 forward-- ly, the arm of the angle lever is moved upwardly, raising the billet baci; to the plane of the top side of the bar 79. Thereupon, fluid pressure is admi ted to the pivoted end of the cylinder lili, moving the jaw 93 forwardly and, by action oi the roller `8S, swinging the arm upward. The arrangement is such that the arm @d is moved in its upward billet clamping position prior to the application of the clamping action bythe jaw 95.

End clamping structures are provided for engaging the ends of the billets after they have been clamped by the clamping and turning structures just described. The side plates 52 extend from the clamping and turning structures toward the ends of the table 2S and there is fixed to the extended portions of the side plates 52 a top plate 112, see FGURES 7 and 8. There are a pair of guide members 113 fixed to each top plate 112, as by cap screws 1114, these members extending in parallel spaced relation and are in form similar to the guide members Sil. A block 115 is positioned on the plate 112 and the lower portions of its sides are formed avith grooves for sliding cooperation with the guides 113. An angle plate 116 is xedly secured to the top of the block 115 and has an upstanding flange 117 positioned for engagement with the end of the billets B,

The block 115 is moved toward and from the billet clamping and tur ng structures by a piston rod 113 mounted in a cylinder 12d having trunnions 171 mounted in bearings l iixedly secured to the top plate 112. When uid is admitted to the outer end of the cylinder 129, the block 115 is moved to the left, FGURES 7 and S, eiecting movement of the angle flange 117 against the end of the billet positioned in the clamping and turning structures. Preferably, a hardened wear rod 12d is fixed to the harige 117. A switch 125 is mounted on the block 115 and a switch actuator 12o is provided for engagement by the end of the billet B when the clamp is in engagement therewith. The switches 125 are Connecte series in circuity hereinafter described in such manner that the can not be started unless both end clamps are in clamping engagement with the ends of the billet. When duid is admitted to the inner ends of the cylinder 126, tde end clamps are moved to the right, FlGURES 7 and 8-that is, in a direction away from the ends of the billet supported on the billet clamping and turning structure lt has been previously pointed out that the side plates are slidaby mounted on the table top 28 for move- ..-ent in a direction lengthwise oi the table. Referring again to FGURES 7 and 8, a nut 13G is secured to the under side oi the top plate 112, as by screws 131. A screw 132, is iournalled in bearings 133 xed to the table top 2S, as by cap screws 134i, the screw 132 extending through the nut and accordingly being operable, upon rotation, to move the entire and turning assembly in a direction lengthwise of the table 2S. Rotation is imparted to the screw 132. by a motor 135 iixedly secured to the table top 2S and having a speed reducing unit i315, the output shaft 137 of which is connected c iiexible coupling 13S to the screw 132. The is reversible. fx/ith this arrangement, the spacing between the billet clamping and turning structures can be adjusted to accommodate billets of varying length.

A bar Edil is lxedly secured to each of the blocks 115, and extends forwardly and downwardly, and each bar 145i, see FlGURE-S l, 3, 7 and 8, is provided at its outer end with a shoe 2.42 for engaging the actuators of switches 143 mounted on a bar 15rd fixed to the upper end of the vertical members 32. The switches M3 are adjustable along the bar 14M and secured in adjusted position by a screw Edd. The switches 143 control the circuit to the reversible table actuating motor 45. Eecause the bars 1d@ are fixed to the billet end clamping structures, the extent of the reciprocating movement ot the table is thus automatically controlled in propord tion to the length of the billet being ground to assure that the travel ot the table is sufcient to grind the entire length of the billet.

The grinding wheel mount is carried by a support slidably mounted on columns 16? 'ertically mounted on a carriage having movement toward and from the table 28 in a direction transversely thereof. The carriage is formed or channel shaped side members J1 arranged in spaced apart pairs and fixed in this relation by top plates 162 welded to the top flanges of the channel members, see FEGURES 2 and 3. The side members are connected by a plurality of transversely extending I-bearn members 163 on which are fixcdly secured plates 16d, 155. The lower ends of the columns 16) are formed with cylindrical anges .166 securely attached to the plates 154, 165, by cap screws 157. Supporting wheels 163 are joui-nailed between the side channel members 161 at opposite ends thereof. The rollers 168 are grooved at their peripheries for rolling engagement on rails 17@ iixedly secured to l-beams T171. The carriage is reciprocated along the rails 17@ by a cylinder and piston structure comprising a cylinder 173 mounted at its rear end to a cross member 174 fixed to the l-beams 171, see FlGURE 6. The pistou rod 17S is connected to an angle bracket 175 secured to the center cross members 153.

A plate 177 is fixed to the upper ends or" the columns The columns 16? are hollow and there is a weight in each oi the columns, see FIGURE 2. rl`hese weights are attached to cables 181 trained over sheaves 18.2 ,iournalled in brackets 1e3 secured to the top plates 177. The cables 131 extend downwardly and are atte hed to brackets lt secured to a cylindrical collar The cylindrical collar consists of part of the wheel mount support, it being fixe-:l to transverse members 187, see FlGURE 5, which at their ends are Welded to cylindrical members 13d slidably mounted on the columns 16%. The collar 185' is further secured by gusset members 1% welded to the collar and to the cylindrical members 1538. A cylindrical plug Ebd is mounted in the collar 135 and carries a plate 192. The plug 19d is rotatably mounted in the collar 1135 and means, not shown, is provided for securing it in fixed relation to the collar.

The plate E77 is apertured to receive a gear rack 197 secured to one of the cross members 137 by a bracket 1% ixed to the cross member and fixed to the rack by cap screws The upper portion of the rack 97 is in mesh with a pinion gear 2li@ carried on the output shaft 291 of a gear reducing unit coupled to a reversible motor 293 mounted on a bracket 2de fixed to the top plate 177. The plat 177 is partially supported by inclined brackets xed th ir lower ends to the carriage top plate under side of the plate at their upper ends to the see 2 and 3. The reversible motor 2%, ouch the pinion and raclr arrangement, serves to move s the wheel mount support 'vertically on the columns 16d.

The wheel mount consists of a pair of channel shaped arm members 22@ xed at their inner ends to a plate 221, see FIGURE 5. rhere are a pair of similar arms 223 fixedly secured to the plate 192 and extending forwardly tl ereirom through apertures 224i formed in the plate 221. These arms 223 carry, at their outer forward ends, bearing blocks and there is affixed to the under sides of the arms 2.29, intermediate their ends, bearing blocks 2227. A shaft 22S extends through the bearing blocks 2.25, 227, whereby the arms Ztl and the plate 221 are pivotally mounted on the shaft 22S. Bearing brackets 23@ are secured to the under sides of the arms 22@ adiacent the outer ends thereof, and a grinding wheel arbor 231 is journal-ed in these bearings and is provided with means for clamping a grinding wheel 232 for rotation with the arbor. This rotation is effected by a grinding wheel operating motor 233 mounted on a plate 235 lixedly mounted on the plate 2.2i, as by cap screws 236 extending through the plate 235' and a spacer bar 237 and threaded into the plate 221. The motor 233 is operatively connected to the wheel arbor 2.3i by a belt drive 238. Pivotal movement of the arms and plate 221 in a clockwise direction, FIGURE 2, is limited by bolts 249 positioned in the upper ends of the plates 192, 221. A helical compression spring 243 is mounted on each of the bolts 2e@ and yieldingly urges the plate 221 and the arms 22@ in a direction away from the plate 192 Ythat is, in a direction to move the grinding wheel 232 toward the billet B positioned in theclamping and turning structures on the reciprocating table.. U-shaped members 243 are tired to the plate 221 and extend upwardly, and over the top edges of the plates 192, 22l, and downwardly rearwardly of the plate 2.92. These members 243 simply serve as a safety precaution to limit downward pivotal movement of the grinding mount about the shaft in the event the bolts Zei) should become defective.

rl`his arrangement provides for limited vertical movement of the wheel mount relative to the support, and the wheel is yieldingly urged into engagement with the billet by the weight of the wheel mount and the wheel assembly, plus the action of the springs 24E.. This forms an important feature of my invention as it permits automatic up and down adjustment of the support in response to a slight variation in the pressure between the grinding wheel and the billet, all whereby response to even a slight change in wheel pressure permits the motor 2%3 to change the elevation ot the support in quick response to even a slight variation in wheel pressure.

The grinder stops with the wheel mount in the upiorward position. The machine can not start unless a billet is clamped in the billet clamping and turning structures, and the end clamps i124 have been moved into clamping engagement with the ends of the billet, and the contacts of the switches 125 closed. it a billet is properly clamped on the table, the machine may be started. The wheel mount moves downwardly to bring the wheel into contact with the front corner edge of the billet and at this time, the table is being reciprocated. Upon each reciprocation of the table, a predetermined amount of fluid is admitted to the front end of the cylinder l' to cause the support carriage to move rearwardly a short distance, this operation being repeated with each reciprocation of the billet supporting table until the grinding wheel 232 has finished grinding the upper liat side of the billet, whereupon the wheel mount support is moved upwardly and forwardly, during which time the billet clamping and turning structures are operated, as previously described, to bring the next side of the billet upwardly. When the billet has been reclarnped, the wheel mount support will move downwardly and the second side of the billet will be ground. rhis cycle of operation is repeated until all tour sides of the billet have been ground, whereupon a billet storage and feeding conveyor is operated to move a new 1`illet into the clamping structures and to push the ground billet inwardly from the clamping structures so that it may drop onto an inclined roll conveyor 25h. This conveyor is positioned rearwardly of the billet reciprocating table and extends lengthwise thereof, see FGURE 3, and is constructed with a series of rolls 25l. The ground billets gravitate down the conveyor 25d and strilte against a spring pressed plate 252 which actuales a switch controlling a solenoid operated valve to admit fluid to the lower end ot a cylinder 253. Bumper members 25d are iixedly secured to the machine frame and extend upwardly from the conveyor 25h to direct the discharged ground billets onto the conveyor.

There are a series of downwardly inclined beams 255 having their upper ends attached to the inner side rail of the conveyor 25h. The cylinder 253 is pivotally attached at its lower end to a cross member 25e xed to the beams 255. The piston rod 257 is connected to an arm 25d pivote-:l at 259 and having a horizontal arm Zeil normally positioned between a pair of the rolls 25l. vWhen fluid is admitted to the lower end ot the cylinder 253, the arm moves upwardly, effecting movement of the ground billet from the conveyor to the inclined Vbeams 255. The billet storage and in-eed conveyor device may be of any suitable construction such, for example, as that shown in Lowe Patent No. 2,819,563.

rfhe machine is started by rst closing a starting switch 2255 to pull in relay 26e. This circuit extends from supply line 267, wire 26S, closed contacts of stop switch .27%, wire 27E, closed contacts 272, of an overload relay .273 connected in the power supply to the support positioning rnotor 293, wire 2&2, starting switch 255, wire 23E., contacts of switches SL25 on the billet end clamps, closed when a billet is properly clamped on the table, wire 282,

. relay 265, wire 233, to the opposite side 234. of the line.

Relay 26e is provided with contacts 286 to provide a :stick circuit in parallel with the starting switch 265 'through wires 237, 223, contacts 236, and wire 239.

The motor starter 29h is energized to close its contacts 293i, 222, 223, to energize the grinding wheel motor :233. The motor starter 29d also includes a pair of con- :tacts 294. A current transformer 2% is connected in the power line to the grinding wheel motor 233 and sup- ;plies p wer to a full Wave rectilier 2% having an output 297, 293, across which there is connected a relay 299 by wires 36h, 391.

A voltage divider 362 is also connected across the line 297, 293, by wires 324, 3435. The movable contact 3% of tue voltage divider is connected to a wire 3l?? which extends to a potentiometer rheostat 3%, the opposite side of which is connected to the movable Contact Bild of a voltage divider 321 by wire 3l2. The potentiorneter rheostat 3h23 has a shunt in the form of a rectilier 313 connected to the rheostat by wires 314, 3l5.

A regulated supply of DC. voltage is provided on line Si?, SES. The wire Sl is plus, and the wire 298 from the rectiier is plus. T Lere is a circuit connected across the line 317, Slg, consisting of wire 326, limiting resistor 32l, wire 322, voltage divider 321, wire 323, variable resistor 324, wire 325, voltage divider 326, wire 327, potentiometer rheostat 328, wire 329, to wire 313. 1ill/ire 327 is connected through wire 33t) to one side of a control lield 331 of a control device, as a compensated armature-reaction-excited dynamo electric generator, indicated at 332. A device of this type is manufactured by the General Electric Company, and is referred to as a Amplidyne.

The opposite side of the iield 33l is connected to wire 293, through wire 335, contact 336, wire 337, diode 33S, wire 339, contacts 34h, wire 34l, contacts 342, wire 3de, contacts 345, wire 3de, down limit switch 347, carried by the wheel mount support 168, see FIG- URE 6, to wire With the wheel mount in the rip-forward position, and with the circuit energized or automatic pressure control, contacts 342, 3455', are closed. Contacts 33e, 34h, are closed by relay This relay is energized to close contacts 336, 349, by a manually operable switch 351, the circuit being from wire 227, closed contacts 294, of the grinding wheel motor starter, wire 352, contacts 353, wire 354i, contacts 355, wire 355, switch 351, wire 357, closed contacts 358, of back travel limit switch 397, wire 359, relay 35i?, wire 35h, to wire 28d. The closing of contacts 33e, 3dS, completes the circuit from wires 2%, 3l?, to the held 331.

The head positioning motor 2&3 is connected to the output wires 362, 363, of the control device 332. The motor 2% is a reversible motor and its forward and reverse direction is controlled by the polarity imposed upon the control field 331. As previously stated, the DC. source 317, 3m is regulated to supply a reference one, voltage. The alrebraic sum of the output voltages from voltage divider 3H and voltage divider 392 are fed to the feld 331. The output polarity of the control device 331?. is determuied by the polarity of the iield The polarity of this field is determined by the current drawn by the grinding wheemotor 233. When the current drawn by the grinding wheel motor 233 produces a voltage across voltage divider 362 which is `rcater than the reference voltage across voltage divider il, the polarity of eld "3i is such that the output oltage in wires SEZ, 363, of the control device 332 causes tire motor Ztl?, to move the grinding wheel support upwardly, moving the Wheel away from the work. The reverse action is also true, that is, when the reference voltage across the divider 311 is greater than the voltage across the divider 362, tire motor 263 moves the wheel mount support and grinding wheel downwardly toward the work.

The pressure at which the grinding wheel 232 engages the work piece is predetermined or varied as desired by adjusting the Contact 3i() of the voltage divider Eli to increase or decrease the reference voltage.

It will be understood that by so increasing or decreasing the reference voltage etecting change in the pressure between the grinding wheel and the work piece, there is a resultant change in the current drawn by the motor 233 and accordingly, a change in the rectiiier output 297, 293 that is, a change in the voltage across the divider 3%, this bringing about the situation Where the voltage across divider Sil and the feed back or signal voltage divider 362 are equal and opposite in polarity. This results in an algebraic sum of voltages equal to zero impressed upon the field M" ser, so the output in Wires 362, 353, is zero, and the motor 293 comes to rest. Accordingly, the grinding wheel pressure is determined by the setting of the Contact 3l@ of voltage divider 3H and thereupon, the machine will function at that pre-set grinding pressure which, in turn, determines the thickness or amount of material ground ofi from the billet.

if the surface of the billet being ground is not straight for example, it the surface being ground curves upwardly, the bressuire between the grinding wheel and the billet is therefore increased, causing a raise in the voltage across the divider 392, whereupon the wheel mount positioning motor E93 will eect upward movement of the wheel rnounr support to reduce the pressure between the wheel and the billet. As this pressure deeases, tno voltage across divider 3G?, decreases, and en that voltage becomes equal to the voltage across ider Ell, the motor 2593 will cease operation. When the upwardly curved or high spot of the billet is ground or? and the load accordingly decreases on the grinding wheel motor 233, the output voltage across divider 3%2 decreases, effecting reversal of the polarity in tieid 33i, causing the motor 2&3 to lower the wheel mount support until the pressure of the grinding wheel on the billet is re-estabiished to the pre-set value. Actually, these changes in the elevation or" the wheel mount support take plac instantaneously, all whereby the wheel grinding at the pre-set pressure very closely follows the contour of the billet, whereby a uniform thickness of metal is removed from billet.

Returning again to the situation where the wheel mount is in the tip-forward position, that is, with the grinding wheel positioned upwardly from the front corner edge of the billet, the voltage across divider 3%2 will be low divider Sii from the regulated supply. This would result in a relatively high current iiow in the iield 331, effecting rapid downward movement of the wheel mount support by the rnc-tor 2%, whereupon the grinding wheel would engage 4the billet under excessive pressure. To avoid this situation, the circuitry includes components which function automatically to control the operation of 1Q the motor 2&3 to effect a ygradual descent of the motor mount as the grinding wheel approaches the front corner edge of the billet. in other words, the selected pre-set grinding pressure 'is automatically modified during descent of the wheel mount from up position to contact with the billet.

These components include the limiting resistor 323i, voltage divide-rs 311, 326, potentiometer rheostat 325,

and variable resistor 32d. These components, as will be apparent, determine the voltage across divider 3M. After the grinding wheel has descended into engagement with the billet, the variable resistor 324 is shunted to remove it from tbe circuit, and during descen-t of the grinding wheel, the potentiometer -rheostat 328 is automatically adjusted to effect a reduction across the `divider 311.

Due to the frictional engagement between the collars l?, of ythe wheel support and the columns dei), considerably Imore power is required of the motor 203 to start the support downwardly than is required to maintain it `in downward motion. The movable contact 37d off the potentiometer rheostat 32,8 is mechanically coupled with the wheel mount support. Referring to FIGURE 6, this potentiometer rheostat is mounted on a plate 371i mounted for vertical sliding movement on guide rods 372 tixedly secured to a large mounting plate 373 secure-d to one of the inclined column braces 2F35. This plate 37=1 is moved upwardly and downwardly by :a screw 374 operated by a reversible motor 37S. The movable contact 370 -is mounted on a shaft carrying ya pinion 376 engaging a gear 377 to which is affixed arm 373. A weight 37% is attached to one end or" the ann Q73 and the opposite end -is positioned to be engaged by a proiection 386 adjustably mounted in a bracket 3951 fixedly secured to one of the collar members of the Wheel mount suption of the gears 377, 376, and accordingly, rotation of the Contact 37b. The arrangement is such that as the wheel mount support descends, the potentiometer rheostat cuts more resistance into the circuit, thereby reducing the voltage `across the resistor 3111i, reducing the excitation of the ield 333i and accordingly, reducing the speed of the motor 2&3, all whereby the wheel mount support descends at a slow adjusted controlled rate.

hen the grinding wheel 2.32, engages the front corner edges of the billet, the power load immediately increases on the wheel motor 23.3 and accordingly, the output 237, 29S, of the rectifier increases, raising the voltage across the divider 362 and also 'energizing the relay 239 to close its contacts 333, 334. The closed contacts 333 provide a shunt circuit for the variable resistor 32,4, this circuit including Wire 335, closed contacts 383, wire 355, wire 3ST'. Shunting the resistor 324 increases the voltage across the divider 311. raising the potential on wire 33d to eiilect downward movement of the wheel support by the motor through the control device 332.

Due to the fact that the corner edge of he billet presents a relatively small area to the grinding wheel con pared to the flat top side of the billet, it is desirable to establish a rela-tively light grinding pressure between the wheel and the corner edge of the billet compared with the pre-set grinding pressure for the top `hat surface of the billet.

When the wheel mount is in the forward position, contacts 3%@ are oened by shoe 39d, engaging the actuator of switch 322. With the wheel mount this forward position, shoe 391 also is in engagement with the actuator of switch 393, which is a forward travel limit switch controlling duid supely to the cylinder T73. The switches 3%, 393, are mounted ou a plate 394-, sce FIGURE 6. Fthere is a similar plate 395 on which are mounted switches 3%, 397. The plates 394, 39S, are formed with projections 393 Aslidably mounted on rods 4%, the ends of which are Xedly secured in brackets itil secured to one 11 of the base I-beams 171 on which the carriage is mounted, see FIGURE 18. The plates 394, 395, are also formed with projections 462 threaded to receive a positioning screw 433 journalied in the brackets 461 and operatively connected to a reversible motor 4h4- carried by a bracket 435, see FIGURE 17, attached to a plate 4i6 also welded to the beam 171. The thread of the screw 433 engaging the nut portion 402 of plate 394 is the opposite hand of that portion of the screw engaging the nut on the plate 395. Accordingly, operation of the motor 4114 moves the plates and the switches carried thereby toward and from each other. The purpose of this arrangement is .to compensate for the reduction in the diameter of the grinding wheel 232 by the wearing away of the wheel during the grinding operations. This variation of grinding wheel `diameter requires, for eiiicient oper-ation, a like variation in the front and rear limit portions of the wheel mount.

'The shoe 391 is carried on an arm 437 slidably mounted on a bar 438 iixed to the carriage, see FIGURES 6, 14 and 15. The arm 467 is attached to a nut 469 traveling on a screw 41%. This screw is journalled at its ends in bearings 411 `and is operatively connected to a reversible motor 412. This arrangement is operable to adjust the shoe 391 in the direction of travel of the carri-age, or toward and from the shoe 413.

The switches 396, 397, are actuated by the shoe 413 adjustably 'ixed on the bar 493. The adjustment of the shoe 391 is to eiect automatic grinding operations of billets of different cross sectional dimension, such as two, four, tive and six inches. As shown in FIGURE 4, the ixed billet clamping jaw 85 is arranged at the rear of the billet clamping and turning structure-that is, the billets are always clamped against the fixed located jaw 85. The clamping position of jaw 93 however varies according to the cross section of the billet. Accordingly, the switch actuating shoe 413 is not ordinarily adjusted after the machine is set up. However, the position of the shoe 3911 has to be such that the carriage supporting the wheel mount support will move forwardly a suiicient distance to grind the entire top side area of a billet.

There is an arm 414 attached to the nut 409 and extends inwardly over the plate 162 of the carriage frame and has ahxed to its inner end a bar 415. The bar 415 is slidably mounted in bearing blocks 416 secured to the plate 162. The under side of the bar 415 is formed with a transversely extending groove 417. A plurality of switches 41S `are mounted on the plate 162 intermediate the bearing blocks 415. The actuators of these switches are permitted to move upwardly to close the contacts of the switches when the groove 417 is moved in registration with the switches respectively. The switches 418, when actuated, light pilot lamps on the control console of the machine to advise the operator as to the size billet the machine is set to grind.

Returning now to the operation of switch 392, the opening of contacts 39% drops out relays `421), 421. This results in opening the front contacts 422 and closing the back contacts 423 of relay 421, land the opening of front contacts 425 of relay 426. This arrangement provides a circuit from wire 427, now closed contacts 394, wire 42S, potentiometer rheostat 429, Wire 431i, closed contacts 423, wires 386, 387, to wire 325. This means that the potentiometer rheostat 429 is connected in parallel with the potentiometer rheostat 328 and voltage divider 325. This presents a voltage on the divider 311 of a ilower value, whereby the signal voltage in wire 312 becomes more eiective in reducing the plus voltage in wire 33t) to the eld 331, automatically resulting in a reduced pressure between the grinding wheel and the billet while the front corner edge thereof is being ground. As previously pointed out, upon each reciprocation of the billet carriage table, the carriage with the wheel mount and support therefor is moved rearwardly. As the carriage moves rearwardly, the shoe 391 passes out of engagement with 12 the actuator of switch 392, re-closing the contacts 390. This results in again energizing the relays 424i, 421, closing contacts 422, 425, and opening contacts 423. The closing of contacts 422 provides a shunt circuit around the voltage divider 326 and potentiometer rheostat 323. This circuit is established from wire 329, Wire 427, wire 435, closed contacts 422, wires 336, 387, to wire 325. This now provides a voltage across the divider 311 at whatever value the divider is set for to provide the preset grinding pressure to grind the top surface of the billet.

When the carriage moves rearwardly a distance to bring the grinding wheel in proximity with the rear corner edge of the billet, the shoe 413 engages the actuator of switch 396, opening its contacts 436, deenergizing relay 421. However, relay 42@ remains energized because the contacts 39d of switch 392 are then closed. Contacts 423 are again now closed, and contacts 422 opened. This circuitry again puts potentiometer rheostat 429 in parallel with part of voltage divider 326 and potentiometer rheostat 37@ to again reduce the voltage across the divider 311 to provide lighter wheel pressure for grinding the rear corner edge of the bi-llet. This circuit is from wire 329, wire 427, contacts 384, wire 42S, potentiometer rheostat 429, closed contacts 423, closed contacts 425, wire 594, to the movable contact 595 of the voltage divider 326.

It will be observed that in regulating the pressure for grinding the forward corner edge of the billet, as previously explained, the potentiometer rheostat 429 was connected in parallel with the potentiometer rheostat 32S and voltage divider 326, whereas, in the circuit controlling the pressure for grinding the rear corner edge of the billet, the potentiometer rheostat 429 is connected in parallel with potentiometer rheostat 328 and a part of the voltage divider 325. This arrangement permits the operator to adjust the rear corner grinding pressure by movement of the contact 595, this adjustment being independently of the adjustment for grinding the forward corner edge ofthe billet.

It will be apparent that as long as the switch 351 is closed, the machine operates to grind the top surface of the billet at a predetermined set pressure which is automatically maintained regardless of any curvatures in the billet. Also, the arrangement provides for applying selected lighter grinder pressures in grinding the Iforward and rear corner edges of the billet.

If the operator desires to take the machine out of automatic control for manual operation, the switch 351 is opened. A switch 45d is coupled to the switch 351 and when the latter is opened, switch 45S' is closed. The control device 332, in addition to the automatic control lield 331, is provided with a manual cont-rol eld 454. Opening of the switch 351 de-energizes the relay 35i), opening contacts 336, 34), in the control circuit to iield 331 of the regulator 332.

To move the wheel mount support upwardly, the operator can close the normally open switch 456 which provides a circuit from wire 237, wire 457, switch 456, wire 458, normally closed switch 459, wire 461i, reiay 461, wire 452, to the opposite side 284, Relay 451, when thus energized, closes contacts 464, 465. Closing of these contacts provides a circuit from side 47d of a DC. supply, contacts 4&4, wire 471, manual field 454, wire 474, closed contact 475, wire 476, closed contacts 465, to the opposite side 478 of the supply. This arrangement provides power of such polarity on the eld 454 to cause the regulator 332 to actuate the motor 203 to raise the grinding mount support upwardly.

Opening the down switch 459 and closing switch 48) coupled thereto, eifects a circuit from wire 237, through closed switch 431 coupled to the switch 45d, and closed when the latter is opened, thence through wire 432, now closed switch 480, wire 483, closed switch 454i, relay 486, wire 487, to the opposite side 284. Relay 485 closes contacts 493, 491. This establishes a circuit from wire 476, through wire 492, contacts 431i, wires 493, 476, closed contacts 475 of relay 359, wire 474, field 454, wire 471, wire 494, contacts 491, wire 495, to the opposite side 47S. This circuit results in reversing the polarity on the manual control iield 454, causing the wheel mount support to move downwardly. Accordingly, the operator can at any time take the machine out of automatic control and operate the wheel mount support upwardly and downwardly at will.

When the top side of a billet has been completely ground and the carriage reaches the rearmost position, the back travel limit switch 397 is actuated by the shoe 413, FIGURE 6, to open contacts 358 and close contacts 50i). Contacts 500 are connected in series with contacts 501 of an up limit switch 502 mounted on the plate 371, FIG- URE 6. The switch 502 has a pair of normally closed contacts 503 providing a shunt circuit around the diode 338. The purpose of the contacts 503 is to provide a conductive path to the control ield 331 when the positive potential on wire 298 exceeds that on the wire 3136 so that, in the normal operation of the machine, the polarity of the control eld 331 can change in order to maintain the constant pre-set wheel pressure, as previously explained. The diode 338 in the circuit always provides for the how of current through the iield 331 in a direction to move the wheel mount downwardly and the contacts 503, when closed, provide for the iiow of current in both directions to the ield 331.

The closing of contacts 500 of the rear travel limit switch 337 provides, through the closed contacts 591 of the up limit switch, a shunt circuit to the manually operable switch 456, this circuit being through wires 457, 505, contacts 591, wire 506, contacts 599, wire 537, to Wire 45S. As previously explained, this circuit extends to and energizes the relay 461 to apply power to the iield 454 with a polarity to cause the control device 332 to energize the motor 263 to eiect upward movement of the wheel mount.

When the wheel mount has moved upwardly away from the billet, the up limit switch 502 is actuated by engagement with a cam 566 adjustably mounted on the bracket 381, see FIGURES 6 and 16. This effects opening of the contacts 561 and 503, breaking the energizing circuit to relay 461 and stopping movement of the motor 203, the diode 338 being a block to the ilow or current to iield 331 to cause upward movement of the wheel support. The switch 592 is also provided with a third pair of contacts 567 which now close to establish a circuit from source 508, wire 599, contacts 567, relay coil 519, wire Sil, contacts of forward limit switch 393, wire 512, to the opposite side 513 of the source. The closing of relay contacts 514 establishes a circuit from wire 563, contacts 514, solenoid valve 515, wire 516, to the side 513. The valve operates to apply fluid pressure to the rear end of the cylinder 173 to effect forward movement of the carriage.

The closing of contacts 567 also establishes a circuit through wire 518, relay coil 519, wire 529, contacts 521 of a timer 522, wire 523, to the opposite side 513. The timer is also Venergized from wire 51S, wire 525, wire 526, to the side 513. Contacts 536, of relay 519, close and establish a circuit from wire 5&8, through wire 531., contacts 539, wire 532, solenoid valve 533, wire 534, to the side 513. The solenoid valve thus energized applies iluid to the inner or free end of the cylinders lidi to unclamp the jaws 35, 93, from the billet. lt also applies uid to the inner end of the cylinders 125i to move the billet end clamps 125 outwardly away from the billet.

An arm 535 is afiixed to the clamp block 125 and carries a shoe 536 which, when the clamps are in open position, engage and actuate a switch 537. The closing of switch 537 establishes a circuit from wire 533, through wire 53S, contacts 537, wire 539, switch 545, see FIG- URES 9 and ll, wire 541, solenoid valve 5K2, wire 543, to the opposite side 513, The valve 542 thus energized, applies huid to the pivotal end of the cylinder 77 to move its piston rod S3 to the left, FIGURE 1l, and move the billet supporting arm 8) downwardly to permit the billet to roll into the notches of the turning structures. When the arm Si) is in down position, the depending leg portion 81 of the arm engages the switch 540 to open the circuit to the solenoid, reversing the application or" fluid to effect upward movement of the arm and to replace the billet on the bar 75. Upon the completion of this turning operation of the billet, the timer 522 has timed out to return the solenoid valve 533 to normal position, applying iluid to the opposite end of the cylinders 102, 12), to move the jaws 85, 93, into clamping engagement with the vertical sides of the billet and the end clamps 125 into engagement with the ends of the billet.

Vifhile this turning operation has been taking place, the carriage has been moving forwardly and the shoe 391 has engaged the forward travel limit switch 393, FIGURE 6, opening the contacts to break the circuit to the relay 5l@ and the circuit to the solenoid valve l5, controlling the supply of iluid to the cylinder 173. It will be apparent that as the carriage moves forward, shoe 13 disengages from the back travel limit switch 397, opening the contacts 541% which, in turn, opens the shunt circuit around switch 456 to the up relay 461, and this relay becoming deenergized, re-establisnes its contacts 342, 355 and now closed contacts 35S of the rear travel limit switch 397 reestablishes the circuit for energizing the relay 350, closing its contacts 336, 34%, whereby together with the closed contacts 3452, the circuit to the automatic control lield 331 is now reestablished and the control device 332 will enerize the motor 293 to move the wheel mount support downwardly for the grinding of the side of the billet, now positioned upwardly, in the manner previously explained.

Whatl claim is:

l. A grinder comprising a table having clamping means for clamping a work piece in fixed position thereon, means operable to effect reciprocation of said table, a suppori: mounted for vertical movement, a grinding wheel arbor carried by said support and mounted for limited vertical yielding movement relative to said support, a grinding wheel carried by said arbor, an electric motor operatively connected to said arbor for etlecting rotation of said grinding wheel, means for effecting relative movement between said table and said support in a direction transversely of the reciprocable path of said table, a power circuit for supplying said motor and means operable upon the current in Said circuit exceeding a predetermined value to move said support upwardly and, upon the current in said circuit being less than a predetermined value, to effect dow ward movement of said support.

2. A grinding machine comprising a work piece supporting table, a support mounted for vertical movement, a grinding wheel mount carried by said support, a grinding wheel journalied in said mount above said table, said mounted having limited vertical movement relative to said support, means yieldingly urging said mount downwardly to cause sai grinding wheel to engage a work piece on said table, reversible means operable in forward direction to raise said support and in reverse direction to lower said support, motor operatively connected to said grinding wheel for rotating the same, a power circuit for supplying said wheel motor, electro-responsive means connected to said power circuit and operable upon the current in said circuit exceedinI a predetermined value to operate said reversible means in forward direction and being operable, upon said current being less than a predetermined value, to effect operation of said reversible means in reverse direction.

3. A grinding machine comprising a work piece supporting table, means operable to effect reciprocation of said table, said table having means to clamp a work piece thereon, a support mounted for vertical movement, a grinding wheel mount pivotally connected to said support, a grinding wheel journalled in said wheel mount, an electric motor operatively connected to said grinding wheel for rotating the same, said wheel mount being movable about said pivotal connection toward and from said table, means operable to effect relative movement between said table and support in a direction transversely of the teciprocable path of said table, a power' circuit for supplya ing said grinding wheel motor, power operated reversible means operable in forward direction to raise said support and in reverse direction to lower said snppor't, electroresponsive rneans connected to said power circuit and operable upon the current in said circuit exceeding a pfe`= determined value to operate said reversible means in fer'- ward direction and being operable, upon said current be; ing less than said predetermined value, to effect operation of said reversible means in reverse direction.

4. A billet grinder comprising a table having clamping means for clamping a billet in fixed position thereon, means operable to effect reciprocation of said table, a carriage mounted for horizontal movement toward and from said table in a direction transversely of the reciprocable path of said table, a vertically disposed column mounted on said carriage, a support slidably mounted on said column for Vertical movement toward and from said table, a grinding wheel arbor carried by said support and having limiting vertical movement relative thereto, a grinding Wheel mounted on said arbor, a grinding wheel motor operatively connected to said arbor for effecting rotation of said grinding wheel, a power circuit for supplying said motor, means yieldingly urging said arbor downwardy relative to said support, a support positioning motor connested to said support and operable in forward and reverse directions to eifelct movement of said support upwardly and downwardly respectively, an electro-responsive rnotor control mechanism connected to the power circuit of said grinding wheel motor and operable upon the current in said circuit exceeding a predetermined value to operate said support positioning motor in forward direction and being operable, upon said current being less than said predetermined value, to etlect operation of said motor in reverse direction.

5. A grinding machine comprising a work piece supporting table, means operable to effect horizontal reciprocation of said table, means for clamping a work piece on said table, a support mounted above said table for vertival movement toward and from the same, a grinding wheel mount pivotally connected to said support, a grinding wheel journalled for rotation in said wheel mount, an electric motor operatively connected to said grinding wheel for rotating the same, said wheel mount being movable about said pivotal connection toward and from a work piece clamped on said table, means operable to effect relative movement between said table and support in a direction transversely of the reciprocable path of said table upon each movement of said table in said path, reversible power means operable to effect vertical reciprocation of said support to move the same toward and from said table for movement of said grinding wheel into and out of grinding engagement with a work piece on the table, and control means operable in conjunction with said reversible power means to automatically maintain a substantially uniform preselected pressure between said grinding 'wheel and the work piece.

6. An abrading machine comprising a table having clamping means for clamping a work piece in fixed position thereon, a support mounted above said table for vertical movement toward and from the same, a grinding wheel mount carried by said support and having limited vertical movement relative thereto in a direction toward and from a WorkL piece on said table, a grinding wheel journalled for rotation in said mount, an electric motor operatively connected to said wheel for eifecting rotation thereof', means yieldingly urging said wheel mount downwardly relative to said support, means operable to eifect horizontal reciprocation of said table, means operable to effect relative movement between said table and support in a direction transversely of the reciprocable path of said table, reversible power means to eiiect vertical reciprocation of said support to move said grinding wheel into and out of grinding engagement with a work piece clamped on said table, and means operable to control said power means to maintain a substantially uniform preselected pressure between said grinding wheel and the work piece.

7. A billet grinder comprising a table having clamping means for clamping a billet in fixed position thereon, means operable to eifect reciprocation of said table in a direction lengthwise of the billet, a carriage mounted for horizontal movement toward and from said table in a direction transversely of the billet, a vertically disposed Acolumn structure on said carriage, a support slidably mounted on said column structure for Vertical movement toward and from the plane of said table, a grinding mount carried by said support above said table, said grinding mount including an arbor journalled for rotation about a horizontal axis, a grinding wheel mounted on said arbor and a motor operatively connected to said arbor for effecting rotation thereof, said mount having limited pivotal movement relative to said support about a horizontal axis toward and from said table, reversible power means operable to effect vertical reciprocation of said support, and control means operable in conjunction with said reversible power means to automatically maintain a substantially uniform preselected pressure between said grinding wheel and the work piece.

8. A billet grinder, as set forth in claim 7, wherein said control means includes means adjustable for varying said preselected pressure.

References Cited in the ile of this patent UNITED STATES PATENTS 2,127,877 Maglott Aug. 23, 1938 2,168,596 Hall Aug. 8, 1939 2,278,584 Peterson Apr. 7, 1942 2,290,611 l-lite July 2l, 1942 2,396,775 De Young Mar. 19, 1946 2,651,895 Rocks Sept. 15, 1953 2,862,312 Gosney et al. Aug. 13, 1957 2,961,808 Dunigan Nov. 29, 1960 

5. A GRINDING MACHINE COMPRISING A WORK PIECE SUPPORTING TABLE, MEANS OPERABLE TO EFFECT HORIZONTAL RECIPROCATION OF SAID TABLE, MEANS FOR CLAMPING A WORK PIECE ON SAID TABLE, A SUPPORT MOUNTED ABOVE SAID TABLE FOR VERTICAL MOVEMENT TOWARD AND FROM THE SAME, A GRINDING WHEEL MOUNT PIVOTALLY CONNECTED TO SAID SUPPORT, A GRINDING WHEEL JOURNALLED FOR ROTATION IN SAID WHEEL MOUNT, AN ELECTRIC MOTOR OPERATIVELY CONNECTED TO SAID GRINDING WHEEL FOR ROTATING THE SAME, SAID WHEEL MOUNT BEING MOVABLE ABOUT SAID PIVOTAL CONNECTION TOWARD AND FROM A WORK PIECE CLAMPED ON SAID TABLE, MEANS OPERABLE TO EFFECT RELATIVE MOVEMENT BETWEEN SAID TABLE AND SUPPORT IN A DIRECTION TRANSVERSELY OF THE RECIPROCABLE PATH OF SAID TABLE UPON EACH MOVEMENT OF SAID TABLE IN SAID PATH, REVERSIBLE POWER MEANS OPERABLE TO EFFECT VERTICAL RECIPROCATION OF SAID SUPPORT TO MOVE THE SAME TOWARD AND FROM SAID TABLE FOR MOVEMENT OF SAID GRINDING WHEEL INTO AND OUT OF GRINDING ENGAGEMENT WITH A WORK PIECE ON THE TABLE, AND CONTROL MEANS OPERABLE IN CONJUNCTION WITH SAID REVERSIBLE POWER MEANS TO AUTOMATICALLY MAINTAIN A SUBSTANTIALLY UNIFORM PRESELECTED PRESSURE BETWEEN SAID GRINDING WHEEL AND THE WORK PIECE. 